This invention relates to evaporators for automotive air conditioners, and, more specifically, to evaporators with a built-in expansion valve for such uses.
In conventional air conditioners, an expansion valve is installed midway in the piping leading to the evaporator, or away therefrom, so that the expansion valve and the evaporator occupy a relatively large proportion of the limited vehicle space. The expansion valve thus supported by the piping is directly subjected to jolts during the running of the automobile and tends to become unstable in control. Also, force produced by the evaporator's own weight acts on the connections between the piping and the expansion valve and between the piping and the evaporator, which may cause cracks of the piping and leakage of the refrigerant.
Since air conditioners for use with automobiles are used under rigorous thermal load conditions, the flow rate of refrigerant through the system must be larger than that in household air conditioners and refrigerators. For this reason evaporators for automobile air conditioners usually are comprised of several sets of cooling units arranged in parallel, and refrigerant is distributed to the cooling units through several branched pipes from a header connected to the end of piping on the discharge side of the expansion valve.
Consequently, piping associated with the evaporator is so complex that the efficiency of piping work during assembly is reduced and productivity is limited owing to the presence of many connections. In addition, a large number of connections results in a high probability of refrigerant leakage and low reliability of evaporator performance.